Safety is proven
Experiments on macaques helped to prove the safety of conceiving a child from three parents
In addition, experiments have shown that children inherited mitochondria from macaque fathers, which theoretically should not happen
Biologists have confirmed that the procedure of "conceiving a child from three parents" is safe. To do this, they followed the lives of several generations of monkeys who were born in a similar way. An article with the results of the study was published in the journal Human Reproduction (Ma et al., Germline transmission of donor, maternal and paternal mtDNA in primates – VM).
"We have always been concerned about the long-term safety of such a procedure, including whether it leads to negative consequences in the advanced years of life. Our experiments have shown that at least two generations of monkeys born in this way had no such side effects," said one of the authors of the study, Professor of the Oregon University of Science and Health (USA) Shukhrat Mitalipov (in a press release Long–term study of mitochondrial replacement therapy in monkeys finds no adverse health effects – VM).
Many serious problems in the work of the human body are associated with disorders in the mitochondria – the main "power stations" of the cell. These organelles are unique in that they have their own DNA (it is called mtDNA), which contains instructions for its assembly and operation. Carriers of defective mitochondria usually die at an early age, and in some other cases, for example, with the development of Lee syndrome, they become infertile.
More than ten years ago, biologist Shukhrat Mitalipov developed a special technique for genome transplantation. With its help, nuclear DNA can be extracted from a fertilized egg with mutant mitochondria and placed in an empty egg with healthy "power stations".
This discovery paved the way for the treatment of Lee syndrome and other consequences of the appearance of mutations in mtDNA. However, Mitalipov and his colleagues were not sure that this procedure would be 100% safe. However, this did not prevent the first semi-legal experiments on the conception of a child from "three parents". In the second half of 2010, they were conducted by several groups of adventurer scientists in Mexico and Ukraine.
Mitalipov and his colleagues condemned these experiments and urged to wait for the first results of a long-term safety check of the procedure developed by them. Scientists began this test back in 2009, almost immediately after the creation of the technology of conception of a child from three parents.
As part of these experiments, the scientists raised five rhesus monkeys using the core transfer technique they developed, and then repeated this procedure using the germ cells of these primates. Having raised several generations of monkeys in this way, biologists began to monitor their health and track how the work of their mitochondria changed.
Observations on the one hand showed that after the transplantation of the nucleus of a fertilized egg, no negative long-term consequences appeared in any case. In addition, it protected the monkeys from problems with the work of mitochondria. On average, the share of maternal mtDNA in their cells and blood was about 3%, that is, there were practically no damaged "power plants" in the cells of new generations of monkeys.
On the other hand, the experiments of Mitalipov and his colleagues revealed an interesting and unexpected phenomenon. Analyzing the contents of the cells of new generations of macaques, biologists found in them not only traces of "donor" and "maternal" mitochondria, but fragments of mitochondrial DNA inherited from the fathers of these monkeys.
In the past, scientists believed that mitochondria are transmitted exclusively through the maternal line, since there are no such organelles inside male germ cells. Observations of American biologists show that this is not always the case. Somehow, the paternal mitochondria or copies of their mtDNA can get into the embryo. Scientists hope to find out exactly how this happens.
Nevertheless, the very possibility of such a spread of mitochondria must be taken into account both in the study and treatment of diseases associated with mitochondria, and in paleogenetic studies, where mtDNA is used to track kinship relationships between ancient animals and study the history of migrations of our ancestors, the scientists summed up.
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